Created by Felix4067 on February 19, 2012
Step 1: Cook pasta in boiling water for 7 minutes; add asparagus and cook another 2-3 minutes; drain.
Step 2: Meanwhile, melt butter in a large frying pan and preheat oven to 450F.
Step 3: Add onion to skillet and cook until softened, 4-5 minutes.
Step 4: Combine flour, thyme, salt and pepper in a bowl; add milk and chicken broth and whisk until smooth.
Step 5: Add milk mixture to frying pan and cook over medium heat, stirring frequently, about 5 minutes or until thickened.
Step 6: Remove sauce from heat; stir in lemon juice.
Step 7: Combine all ingredients except Parmesan and bread crumbs in a 3-quart casserole dish.
Step 8: Combine Parmesan and bread crumbs and sprinkle over top of pasta mixture.
Step 9: Bake for 20 minutes, or until casserole is bubbly and bread crumbs are slightly browned.